Sequence Diagram Template

Visualize request lifecycles and service-to-service interactions over time. Ideal for API design, debugging flows, and architecture reviews.

Use this template

What you get

Participant lanes with timeline-style messaging
Horizontal arrows for requests and responses
Easy to adapt for auth, payment, and event flows

What this template is for

This sequence diagram template helps you map the messages exchanged between components, services, or actors in a system over time. Use it to document an API integration, design an authentication flow, explain a microservices interaction, or onboard a new engineer to a complex call chain. A sequence diagram shows not just what communicates with what, but the order and direction of each message — which is the information that matters most when debugging, designing, or explaining a distributed system.

When to use this template

Document a REST API authentication flow with token exchange and refresh steps.
Map a checkout process across frontend, backend, payment gateway, and notification service.
Design a microservices interaction for a new feature before writing any service contracts.
Explain a complex async flow with callbacks or webhooks to a non-technical stakeholder.
Debug a race condition by drawing the actual message order versus the expected order.
Onboard a new engineer to a legacy system by mapping its key request-response cycles.

How to use it

1List the participants — actors, services, or components — as columns across the top.
2Draw a vertical lifeline down from each participant.
3Add horizontal arrows from left to right for requests and right to left for responses.
4Label each arrow with the message name, method, or event.
5Use activation boxes on lifelines to show when a participant is actively processing.